Party telephone-line.



O. B. SCHNERRE.

PARTY TELEPHONE LINE.

APPLICATION mm AUG-28, 1914.

Patented May16, 1916.

a SHEETS-SHEET 1.

0. B. SCHNERRE.

PARTY TELEPHONE'LINE.

APPLICATlON flLED AUG.28, 19x4.

Patented May 16, 1916.

3 SHEETS-SHEET 3- attorney THE COLUMBIA PLANOGRAPH c0., WASHINGTON, D.c.

OTTO B. SCI-INERRE, 0F GALENA, ILLINOIS.

PAR-TY TELEPHONE-LINE.

Application filed August 28, 1914.

To all whom it may concern:

Be it known that I, O'r'ro l3. Sons-nuns, a citizen of the UnitedStates, residing at Galena, in the county of Jo Daviess and State ofIllinois, have invented certainnew and useful Improvements in Party Telephone-Lines, of which the following is a specification.

This invention relates to telephone systems and more particularly tothat class of telephone systems known as party lines, in which more thantwo subscribers are connected on the same line.

The system as at present used presents a number of inconveniences anddisadvantages which makes the use of the same undesirable, the principaldisadvantage being the fact that while two subscribers are talking onthe line a third subscriber may listen in or eavesdrop, and also caninterrupt the conversation by raising and lowering the receiver hook athis station.

Another disadvantage of the present systenris that in calling asubscriber other subscribers on the same line are very often called dueto the fact that the calling or ringing current actuates more than oneof the bells on the same line at the same time.

The object of my invention is to overcome the above set forthdisadvantages of the system as at present employed. 1 provide a meanswhereby one subscriber may call another subscriber without affecting athird subscriber on the same line.

Another object of my invention is to lock out intervening subscriberswhen two subscribers are talking so as to prevent eavesdropping orlistening in or interruption by other subscribers on the same line.

lVhile this invention may be applied under almost any condition wherethe present system is installed it is particularly adapted to ruraltelephone service where there are a plurality of subscribers on a singleline, and who use as a means of calling each other a code system, thatis, one ring for one subscriber, two rings for another and three ringsfor a third subscriber. This system has its disadvantage in that itcalls all of the subscribers at the same time, and also allows oflistening in on the line while two subscribers are carrying on aconversation.

The object of my invention is to provide means for calling which shallautomatically Specification of Letters Patent.

Patented May 16, 1916.

Serial No. 859,097.

lock out other parties on thesame line so as to avoid calling all of theparties on the line .when desiring to call only one of them.

scriber is finished using his telephone, and

also to provide means for warning a subscriber when he neglects toreturn the circuits to normal condition.

With the above and other objects in view my invention preferably residesin the con struction, combination and arrangement of parts and circuitsas set forth in the following specification and illustrated in theaccompanying drawings, in which:

Figure 1 is a view of a telephone system in which threesubscriberstelephones are shown on a metallic circuit, a portion of the circuitbeingshown diagrammatically. Fig. 2 is a diagrammatical view of thewiring of a subscribers telephone and illustrating the arrangements ofthe circuits therein. Fig. 3 is a transverse sectional view of thepreferred form of selective switchwhich I employ. Fig. 4 is a similarview to Fig. 3 showing the parts in a slightly different position. Fig.5 is a view similar to Fig. 3 slightly enlarged, showing the partsenlarged. Fig. 6 is a detailed view showing oueof the circuit closingelements which I employ in the selective call mechanism. Fig. 7 is avertical sectional view taken on the line 77 of Fig. 5.

Similar reference characters indicate similar parts throughout thevarious views of the drawings.

Referring more particularly to the drawings in which the preferredembodiment of my invention is illustrated, the numeral 1 serves toindicate the casing for reception f the telephone and connections. I

2 indicates the ringing crank, and the transmitter is indicated by thenumeral 3.

The numeral 4 indicates the hook and 5 the receiver of the usualconstruction employed in telephones of this character.

No change is made in the arrangement of the telephone circuits proper,the usual pivoted hook being employed and the transformer, condenser,and battery of the usual type being shown in Fig. 2 and indicated by thenumeral 6.

In the preferred form of my invention the telephone sets together withthe mechanism which I provide are arranged in parallel relation on anall-metallic circuit indicated by the letter A. In Fig. 1 there arethree subscribers shown on the line, however, the number of subscriberswhich may be used has no limit. For the purpose of convenience I haveindicated the three subscribers by the numerals 1, 2 and 3.

lVhile I have shown an all-metallic circuit it will be readilyunderstood by those skilled in the art that I may employ a ground returnusing only one line wire.

The mechanism of the various telephones of the subscribers is duplicatedin every case, the only difference being that the circuit closingelements of each of the selective call mechanisms are necessarily placedat different positions so as to be actuated properly.

I will now proceed to describe the circuits and arrangement of apparatuswhich is used in each of the subscribers telephones, however, for thepurpose of convenience I shall describe only one of the stations, itbeing understood that the said station is duplicated in each of thesubscribers stations so far as the electrical connections andarrangement of parts are concerned.

The following is a description of the calling or ringing circuit and itsoperation, the talking circuit making itself apparent when anunderstanding of the ringing circuit has been acquired. I provide asource of pulsating direct current which in the present instancecomprises a generator G having an armature shaft C driven from a crankshaft 0, said crank shaft being rotated by means of a crank 7. Thecircuit indicated by the letter B comprising the wires 8 and 9 is themain circuit which carries the calling current, said wires or conductors8 and 9 join ing the main line wires at 10. The pole changer 11 isinterposed in the circuit B for a purpose which shall be hereinafter setforth. A spring or other suitable means may be utilized for returningthe pole changer to. normal position.

The circuit B is controlled by means of a centrifugal switch actuator12, the said switch 12 being of the usual construction and having a disk13 which is adapted to contact with'one terminal of the circuit 13indicated by the numeral 14, to force the same into contact with theother terminal of the circuit B indicated by the numeral 15. Anysuitable form of circuit closing element may be used at this point. Thesaid centrifugal switch actuator is mounted upon a shaft 16 and motionis imparted thereto by means of a pinion 17, said pinion 17 being inengagement with the large gear wheel 18 mounted on the shaft C. In orderto provide a pulsating current one side of the circuit leading from thearmature of the generator is grounded to the frame thereof and aninsulating bracket 19 is supported on the generator frame. The wire 8 isconnected to the said insulated bracket 19. Lugs 20 are provided atpredetermined points adjacent the periphery of the gear wheel 18, saidlugs 20 being in electrical connection from the grounded portion of thegenerator circuit. lVhen the crank 7 is turned the lugs 20 make andbreak the circuit between the grounded portion of the generator circuitand the insulated contact 19, thereby providing a pulsating current. I

Referring now to the selective call mechanism I provide a casing 21which, as shown to advantage in Fig. 1, is mounted upon the front of thetelephone box 1. The casing 21 contains the selective call mechanism,which in the present instance comprises a large gear 22 mounted upon ashaft 23, said shaft 23 being mounted in bearings 24 in the casing 21.The large gear 22 is in mesh with a small pinion 21, said small pinion2t being mounted upon a shaft .25, and said shaft 25 being mounted inbearings 26 in the casing 21. Disposed exteriorly of the easing 21 andmounted upon the shaft 25 is a ratchet wheel 27. A pawl 28 is inengagement with the ratchet wheel 27 and is mounted for slidablemovement in a bracket 29, the outer end of said pawl 28 being pivotallyconnected as shown at 30 to a rocking lever 31 said rocking lever 31being pivoted at 32, and the lower end of the said rocking lever 31 isprovided with a tip 33 of magnetic material, said lever 31 serving as anarmature for an electro-magnet 34. i

In order to hold the lower end of lever 31 away from the electro-magnet3d 'a coil spring 31 is provided, said coil spring 31 being attached tothe upper portion of the pivoted lever 31. The electro-magnet 3+1 isenergized from a local circuit (Z having a battery 35 disposed therein,and a make and break contacting element 36 for the purpose ofsuccessfully energizing and de'energizing the electro-magnet 34. Thecontacting ele- 1 ment 36 forms the armature for a relay, theclectro-magnet of the said relay being indicated by the numeral 37. Theelectro-magnet 37 is acted upon by the pulsating current in thegenerator G and current is fed to the electro-magnet 37 by means of theWires 8' and 9 of a branch circuit 6, said wires 8 and 9 being connectedto the main conductor wires 8 and 9 at the points 10. From the wires 8and 9 of the circuit 6 branch wires 38 connected at the points 39 to thewires 8 and 9 lead to the electromagnet 37. The electro-magnet 37 is ofthe polarized type, that is, in order for the contact to be closed thecurrent passes through the electro-magnet 37 in a predetermineddirection. A. similar relay or electromagnet 40 is provided, said relay40 being polarized and adapted to operate with the relay 37, that is,the polarity of the relay 40 is opposite to the polarity of the relay 37so that only one if the relays operates at a single moment. The purposeof the relay 40 is to close a local circuit f which serves as theringing circuit, said circuit having therein a battery 41 and a bell 42,a contacting element 43 being acted upon by the electromagnet 40. Therelays 37 and 40 may be of any approved construction, as theconstruction of the same does not enter into the invention.

' From the above it will be seen that when the generator is in operationa pulsating direct current will be fed to the relays 37 and 40. Therelay 37 only, will operate, alternately closing and opening the circuitZ) thereby energizing and de'elnergizing the electro-magnet 34 andcausing reciprocation of the pawl 28 thereby causing rotation of theratchet wheel 27. Rotation of the ratchet wheel 27 will cause the largegear wheel 22 to rotate by virtue of the engagement of the same with thepinion 24 for a purpose which will be hereinafter described. In order toprevent reverse rotation of the ratchet wheel 27 I provide a pawl 44,said pawl 44 being provided with a projection 44, and a rod 45 connectedat the point 46 to the lever. 31 engages with the ratchet wheel 27 andprevents reverse rotation of the same.

Referring now to the selective call mechanism and the circuit closingelements employed therein I provide, as shown to advantage in Figs. 5and 6, upon the large gear wheel 22 a circuit closing element comprisingan arm 47. Disposed on the inner surface of the casing 21 and at apredetermined position I provide a stationary contact 47', said contact47 being adapted to be electrically connected with the arm 47 at apredetermined time, said arm 47 and contact 47 serving to close thecircuit and the relay 40 hereinbefore described for a pur-- pose whichwill be hereinafter set forth. In the preferred form of my invention theterminal 47 comprises a pair of spaced arms and the contact element 47is adapted to pass between the arms and thereby close the circuit, thisfeature being shown to advantage in Fig. 6. One side of the ringingcircuit is connected to the gear wheel 24 as shown at 48. Disposed at apoint substantially diametrically opposite to the circuit closingelement 47 I provide a pivoted pawl 49, said pawl 49 being held in aposition pointing radially of the gear wheel 22 by means of a spring49', for a purpose which will be hereinafter described.

As will be noted in Fig. 5 of the drawings ments 50 is substantially thesame throughout. These circuit closing elements50 are disposed upon theinner face of the wall of the casing 21 which incloses the selectivecall mechanism. For the purpose of convenience I will describe only oneof the circuit closing elements it being understood as set forth abovethat allof'the circuit closing elements are substantially the same inconstruction. I provide a rod 51 slidably mounted in a bracket 52mounted on the exterior of the casing 21. Laterally extendingprojections 52 are formed upon the rod 51 and are adapted to engage incomplemental groove in the bracket 52 whereby to prevent rotation of therod when the same is reciprocated. A pin or any other suitable means 53is provided upon the rod 51 and a spring 54 is interposed between thepin 53 and the casing 21 so as to always tend to force the rod 51 in anoutward di rection from the casing 21. The outer end of the rod 51 isprovided with an insulated handle 51. The opposite end of the rod 51 isprovided with a circuit closing ele ment which I desire to employ andwhich comprises, as shown to advantage in Fig.

7, a pivoted element 55, said pivoted element 55 being in electricalconnection with the casing 1 and grounded thereto. A spring 56 serves toretain the pivoted element 55 in the position shown in Fig. 7, a stop 57being provided to limit the downward movement of the pivoted switchelement 55.

From the above it will be seen that the pivoted element 55 forms oneside of an electrical circuit. The opposite side of the 117 electricalcircuit is connected to a stationary electrode 58, said electrode beingmounted upon the rod 51 at the point 59 and insulated therefrom. Currentis-fed to the member 58 by means of a lead wire 60, said lead wire beingin an electrical connection with an insulated binding post 61 to whichthe opposite side of the electrical circuit is connected. The operationof this device is as follows :-WVe will assume that the gear T wheel 22is being rotated by means of the pawl 28. Forcing one of the contactingor circuit closing elements 50 inwardly by means of the insulated handleor button 51 into the path of the pawl 49 on the wheel 22 will cause thepivoted element 55 to be forced into contact with the stationary switchelement 58 when the pawl A9 engages the under side thereof. The purposeof the circuit closing elements 50 is to energize the electro-magnet 62,said electro-magnet 62 serving to act upon the pivoted armature 63 whichallows the pivoted contact arm 6& to be drawn down into contact with oneterminal 65 of a wire 66, said wire 66 being one of the wires of thetalking circuit of the telephone set 6. A wire 67 is connected at 68 tothe wire 9 of the circuit 6, said wire 67 being connected to the pivotedarm 64: at the point 69. A spring 70 serves to assist the arm G t incontacting with the terminal 65 of the wire 66. The circuit of theelectromagnet 62 is not only controlled by the contacting element 50 butis also controlledby the arm 6 1, a switch means being provided at 71and adapted to open when the arm 64 is moved into contact with theterminal 65. The opposite end of the pivoted arm 6% is provided with alug 6% said lug 6t serving to close a circuit 9 as indicated at 72 for apurpose which will be hereinafter set forth. The portion 6 1 isinsulated. from the arm 6%, said insulated port-ion, indicated by thenumeral 73 extending slightly beyond the end of'the pivoted arm 6% andadapted to close a local circuit 6 at the point 7%, said circuit 6serving a purpose which will be set forth in the operation of thedevice, but referring to the same in a general way, serves to energizethe electro-magnet 11 of the pole changer 11.

From the above it will be seen that when the electromagnet 62 isenergized the armature 63 thereof will be attracted releasing thepivoted arm 64 and allowing the same to come into contact with theterminal 65. This will break the circuit of the electromagnet 62 and atthe same time close the talking circuit and operate the pole changer 11.It will be understood that the arm 6% only closes the circuit for thecalling station, the selective call mechanism comprising the gear wheel22 and the circuit closers 50 serving to close the circuit at the calledstation. The contacting element 47 has no function at the callingstation as the same is not in contact with the stationary contact 17,however, at the station called the contact element 17 will be inelectrical contact with the stationary contact 47 completing the 3. Allof the gears 22 rotate in synchronisnr that is whenstation 1 moves throuh a quarter turn stations numbered 2 and 3 move through the samedistance. At the moment that the circuit is made in the called stationthe talking circuit for that station is complete and also the ringingcircuit, thatis the relay 10 will be energized closing the circuitindicated by the letter F and ringing the bell 42. All of the relaysoperate simultaneously, and also are adapted to change when the polechanger at the calling station is actuated. Y

The circuit of the electro-magnet 62 is completed through the wire 75joining the casing 21 at the point 75 through one of the contact members50 to the wire 76 and thence to the opposite side of the circuit 1). Inorder to prevent the operation of the electro-magnet 62 after it hasperformed its function and while the parties are talking the circuit hasnot only been broken at 71 but is broken at 77 so that at no time afterthe parties have been called is there a possibility of short circuit dueto the electromagnet 62 becoming energized. A short wire 38 connects therelay 10 with the opposite side of the circuit, one of the wires 38forming the other side of the circuit. In order to indicate the positionat which the variousgears 22 are I provide hands H which are carried onthe end of the shaft 23 and are disposed exteriorly of the casing 21..

The operation of my invention is as follows, it being understood thatthe various selective call mechanisms are in the position as indicatedin Figs. 2, 3 and 4.- and when the same are at normal, Fig. 2 indicatingthe conditions at station #1, Fig. 3 indicating the conditions atstation #2 and Fig. 4 indicating the conditions existing at station #3.lVe will assume that station 1 desires to communicate with station #3and to do so without appraising station #2 of the fact. To attain thisobject atthe calling station, in this instance station #1, the button orswitch 3, as shown in Fig. 1, will be pushed. The crank 2 will now berotated causing the centrifugal switch 12 to close the circuits at letand 77. The lugs 20contacting against the stationary member 19 willcause a pulsating current to be delivered to the main line wires A,thereby energizing all of the relays, in this case relays 37 throughoutthe line. In this manner all of the selective calling mechanisms will berotated synchronously, until the pawl 49 on the wheel 22 at station #1contacts with the pivoted switch closing element 55 of thebutton 3. Atthe time that the circuit which the button 3 controls is closed the gear22 at station #3 carrying the contact arm. 47 will have completedthree-quarters of a revolution thereby contacting with "the stationaryelement 47 and completing the ringing circuit for station #3. Thetalking circuit has not yet been completed because'the receiver at staation #3 has not been raised from the hook. At the moment thatthe pawl 19contacts with the member 55 a circuit is completed through theelectromagnet 62, attracting the armature 63 and allowing the arm 64 tocomplete a circuit through the wires 66 thereby completing the talkingcircuit for the home or calling station. At this moment the insulatedportion 74: on the arm 64: engages the circuit controlling switch 74thereby closing the local circuit 6 which has a battery 6 therein. Thiswill energize the pole changer 11 and cause the same to reverse thepolarity of the ringing current. All of the relays 37 will at this timecease to operate, thereby stopping all of the selective call mechanismssimultaneously, and the relay 40 at station #3 will be energized andcause the bell 42 to ring thereby appraising the subscriber at station#3 that he is being called. In order for the relay to operate it isnecessary that the arm 17 being in connection with the arm 47 and sincestation #3 is the only station at which this condition exists relay 40will be the only one actuated. Immediately upon ceasing to rotate thecrank 2 the ringing circuit and also the main generating circuit isbroken at station #1, the pole changer 11 returns to normal position atthis time. The receivers at both stations may be now raised from theirrespective hooks and a conversation carried on. If station #2 desires tolisten in while stations #1 and 3 are conversing he will find itimpossible as, as shown to advantage in Fig. 3, the contact 47 will beat that time away from the contact &7 so that the talking circuit of thestation #2 has not been completed thereby preventing the party fromlistening to the conversation from station #1 and 3. When theconversation has ceased and stations #1 and 3 desire to hang up the arm64 must be reset and in order to provide for this a handle 80 has beenprovided, a slight upward pull on the handle 80 will bring the end ofthe arm 64 pass the armature 63 and allow the spring 63' which actuatesthe armature 63 to return the parts to normal position. Should thesubscriber at station #1 neglect to return the arm 64 to normal positionand place the receiver on the hook as indicated in the telephone set 6,a circuit will be closed at 8, this circuit being indicated by theletter G having wires 82. This circuit G has the bell 4:2 and battery4L1 interposed therein and upon placing the receiver on the hook thebell will be immediately energized giving a warning and indicating thatthe arm 64 has not been returned to normal position.

When the subscriber at the calling station is through talking the saidsubscriber must ring oil", and this will cause the pointer on the dialto move away from any number so that any other subscriber on the linemay tell by looking at the dial whether the line is busy or not.

Any number of stations may be placed on the one line and it will benoticed that each station has as many circuit closing elements in theselective call mechanism as there are telephones, minus one. Should station #2 desire to call station #3 or #1 or vice-versa the same operationwill be performed in each case.

From the above it is through that a clear and comprehensiveunderstanding of my invention may be had and while I have shown anddescribed a specific form for my invention I desire that it beunderstood that I may make such changes in the details thereof whichshall not depart from the spirit and scope of the appended claims.

Having thus described my invention,

what I claim and desire to secure by Letters Patent, is

1. In a selective telephone system, a main line circuit embracing aplurality of stations and adapted to conduct talking and ringingcurrents alternately, means at each station for calling one of the otherstations and automatically looking out the intervening stationscomprising a selective call mechanism and a pair of oppositely polarizedrelays in multiple in a common circuit for controlling the ringing andtalking circuits at each station, and a pole changer controlled by theselective call mechanism for reversing the polarity of the circuitleading to the relays.

2. In a selective telephone system, a main line talking and ringingcircuit embracing a plurality of stations, sources of current at eachstation, a selective call mechanism associated with each station andinterposed in the calling circuits, oppositely polarized relays, one ofsaid relays at each station being adapted to actuate the selective callmechanism when the calling current is in a certain direction, the otherof said relays being adapted to sound an" alarm or calling bell when thepolarity of the circuit is re versed, said selective call mechanism ateach station operating synchronously from a calling station, each ofsaid selective call mechanisms excepting the station called beingadapted to automatically cut ofi the intervening stations not called.

3. In a selective telephone system, a main line talking and ringingcircuit embracing a plurality of stations, sources of current at eachstation, a selective call mechanism associated with each station andinterposed in the calling circuits, oppositely polarized relays, one ofsaid relays ateach station being adapted to actuate the selective callmechanism when the calling current is in a certain direction, the otherof said relays being adapted to sound an alarm or calling bell when thepolarity of the circuit is reversed, said selective call mechanism ateach station operat ing synchronously from a calling station, each ofsaid selective call mechanisms eX- cepting the station called beingadapted to automatically cut off the intervening staa at each stationhaving a source of pulsating current associated therewith for actuatingall of said calling mechanisms and a circuit closing element at eachstation for controlling the talking and ringing circuits of the stationcalled and calling, and a switch means associated with the source ofelectrical energy for closing the ringing circuit when the talkingcircuit is broken, said switch means comprising a pair of polarizedrelays in multiple.

5. In a selective telephone system, including a main line circuitembracing a plu rality of stations, a selective call mechanism at eachof said stations and operable from any one station, said selective callmechanisms operating synchronously, oppositely polarized relays at eachstation, one of said relays adapted to actuate the selective callmechanism, and the other of said relays being actuated by the saidselective call mechanism. for closing the ringing circuit at the stationcalled, and means associated with said selective call mechanism andactuated thereby for closing the talking circuit at the station calling.

6. In a selective telephone system, a main line circuit embracing aplurality of stations, selective call mechanisms at each of saidstations for calling the other stations on the same line, said selectivecall mechanisms comprising a rotary switch actuating element, circuitclosing elements associated with said rotary switch actuating elementand controllable thereby, said rotary switch actuating element beingoper ated by step by step movement, a relay actuating said step by stepmovement, said relay being energized by means of a pulsating directcurrent of a predetermined polarity, said rotary switch actuatingelement adapted to close one of said circuit closing elements forconnecting the talking circuit of the calling station and energizing theringing circuit of the station called, and means associated with theselective calling mechanism for automatically stopping the same when apredetermined position has been reached.

T. In a selective telephone system, a main line circuit embracing aplurality of stations and adapted to conduct talking and ringingcurrents alternately, a switch means asso-" ciated with the source ofenergy for closing the ringing circuit when the talking circuit isbroken, and a pair of polarized relays in multiple associated with saidswitch means.

8. In a selective telephone system, a main line circuit embracing aplurality of stations and adapted to conduct talking and ringingcurrents alternately, means at each station for calling one of the otherstations and automatically looking out the intervening stations, aswitch means associated with the source of energy for closing theringing circuit when the talking circuit is broken, and a pair ofpolarized relays in multiple associated with said switch means.

9. In a selective telephone system, a main line circuit embracing aplurality of stations adapted to conduct talking and ring ing currentsalternately, a selective call mechanism at each station operable fromany one station for the purpose of calling another station and lookingout the intervening stations, a switch means associated with the sourceof energy for closing the ringing circuit when the talking circuit isbroken, and a pair of polarized relays in multiple associated with saidswitch means 10. In a selective telephone system, a main line circuitembracing a plurality of stations, talking and ringing currents at eachstation, a circuit closing element at each station for controlling theringing and talking circuits of the station called and calling,., aswitch means associated with the source of energy for closing theringing circuit when the talking circuit is broken, and a pair ofpolarized relays in multiple associated with said switch means.

11. In a selective telephone system embracing a plurality of stationsand adapted to conduct talking and ringing currents alternately, meansat each station for calling one of the other stations and automaticallylooking out the intervening stations, and a pair of polarized relays inmultiple for controlling the ringing ,and talking circuits at eachstation.

12. In a selective telephone system, a main line circuit embracing aplurality of stations, talking and ringing circuits at each stationassociated with the main line ci rcuit, a selective call mechanism ateach sta'- tion operable from any one station for the purpose of callinganother station and automatically locking out the intervening station,pawl and ratchet mechanism associated with the selective call mechanism,a pair oi? polarized relays in multiple for controlling the talking andringing circuits at each station, and a source of pulsating'uni-direc-itional current at each station for actuating the respective pawl andratchet mechanism of the selective call mechanism synchronously of theother station on the same line.

13. In a selective telephone system, a main line circuit embracing aplurality of stations, talking and ringing circuits associated with themain line circuit at each station, a selective call mechanism at eachstation operable from any one station for the purpose of calling anotherstation and locking out the intervening station, pawl and ratchet meansassociated with the selective call mechanism and a source of pulsatinguni-directional current at each station for actuating the respectivepawl and ratchet mechanism of the selective call mechanism operatingsynchronously of the other stations on the same line, and a centrifugalswitch associated with the source of pulsating current for controllingthe main ringing circuit and opening the same when the talklng circuitis in use.

14. A selective telephone system, includcalled, means ing a main linecircuit embracing a plurality of stations, selective call mechanism ateach station synchronously actuated from a calling station, a circuitand a relay at each station for actuating each of said selective callmechanlsms, a circuit controlled by each of said selective callmechanisms for energizing the talking circuits of each stationassociated therewith for sounding the call bell of the station called,and a pair of polarized relays in multiple associated with the source ofelectrical energy for closing the ringing circuit when the talkingcircuit is broken.

In testimony whereof I aflix my signature in presence of two witnesses.

OTTO B. SCHNERRE. Witnesses:

T. H. SCHNEREE, HENRY STROHMEYER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

- Washington. D. G.

